Air Compressor Governor needed

[tomc]

Hi, I need one for our 3 inch scale air pump. I would like it to go to 80 psi or so and stop the compressor and come back on about 75. Anyone have a working one to sell or plans for one?

Tom C.

[Steggy]

Hi, I need one for our 3 inch scale air pump. I would like it to go to 80 psi or so and stop the compressor and come back on about 75. Anyone have a working one to sell or plans for one?

Tom C.

Are you looking for electric control, mechanical, ???

[tomc]

mechanical as no electrical on engine to hook to although that mite get me to add a battery.

Tom C.

[Harlock]

Who makes the 3" scale compressor?

Thank you,

-Mike

[johnpenn74]

Little engines has a kit.

[Steggy]

mechanical as no electrical on engine to hook to although that mite get me to add a battery.

Tom C.

The reason I asked about how you want to control your compressor is because the air compressor on my F7 is continuously driven from the prime mover, and thus requires external loading and unloading to maintain air pressure in the proper range. I use a normally-open solenoid valve to load and unload the compressor as needed. I also have a normally closed solenoid valve piped into the bottom of the main air reservoir to drain condensate.

Control is achieved with a non-adjustable pressure switch (purchased item) wired to a control module that I designed and built. The module has the logic required to sequence the two valves to regulate air pressure and keep condensate out of the main reservoir. The locomotive's 12 volt electrical system supplies the juice needed to make it work.

Operation is as follows:

1. As long as air pressure is higher than the cut-in point (~90 PSI on my F-unit) the compressor unloader valve will be de-energized and therefore open, preventing the compressor from charging the reservoir. The reservoir drain valve will also be de-energized, which means the valve will be closed.
2. When air pressure drops below the cut-in point, the pressure switch will close, initiating the control sequence. The first step in the sequence is to energize the reservoir drain valve for approximately one second, causing it to open and discharge air and condensate from the reservoir.
3. In the next step, the control module will de-energize the reservoir drain valve, causing it to close. Simultaneously, the compressor unloader valve will be energized, causing it to close. The compressor will commence charging the reservoir.
4. In the final step, which occurs when reservoir pressure has reached cut-off (100 PSI in my F-unit), the compressor unloader valve will be de-energized, causing it to open and unload the compressor. The air compressor and control system is back to the state described in step 1 above.

The above sequence is prototypical for many Diesel locomotives, although in some cases, reservoir drain valves may also be cycled on a time schedule. In practice, I found that cycling the reservoir drain once per compression cycle was sufficient.

As for your desired pressure range, a five pound differential will required an adjustable pressure switch—fixed ones aren't that close.

Does this sound like what you are looking for?

[Harold_V]

As long as air pressure is higher than the cut-in point (~90 PSI on my F-unit) the compressor unloader valve will be de-energized and therefore open, preventing the compressor from charging the reservoir.

Interesting. Wish you'd have commented on the state of the compressor motor, which I imagine is also not running at this point. I understand the unloading, as my 5 horse Quincy works that way (motor starts, hydraulic pressure rises, closing the valves), but it also cycles the motor on and off, which is how yours work, I suspect. Leaves me with a question, though, when you said "preventing the compressor from charging the reservoir", possibly implying that the motor is running at this point, but not compressing.

H

[Ironman1]

I have a Quincy 325 and due to poor power supply (since corrected) I had to be able to unload the head but keep the motor running, or never be able to run anything else when the compressor started up.
I plumbed in a D-2 air governor from a truck, cost $11. It lifts the valves in the head at 125psi and drops them to start pumping at 100.
Way to low pressure for my likes but I was able to get by til a new pole and transformer fixed the power issue.

[SZuiderveen]

Try Nelson's site

http://www.nelsonslocomotive.com/Heisle ... essorV.htm

Steve

[Steggy]

As long as air pressure is higher than the cut-in point (~90 PSI on my F-unit) the compressor unloader valve will be de-energized and therefore open, preventing the compressor from charging the reservoir.

Interesting. Wish you'd have commented on the state of the compressor motor, which I imagine is also not running at this point. I understand the unloading, as my 5 horse Quincy works that way (motor starts, hydraulic pressure rises, closing the valves), but it also cycles the motor on and off, which is how yours work, I suspect. Leaves me with a question, though, when you said "preventing the compressor from charging the reservoir", possibly implying that the motor is running at this point, but not compressing.

H

Harold, I'm describing the air compressor in my F7, which is mechanically driven from the prime mover and hence is continuously running.

[Harold_V]

Thanks, BDD. I didn't understand how it was powered. That all makes sense. The compressor is running if the engine is moving, but provides air only when the unloader closes the valves.

I reread your original post and see you already made mention. Seems to have slipped right past me!

H

[cbrew]

Hi, I need one for our 3 inch scale air pump. I would like it to go to 80 psi or so and stop the compressor and come back on about 75. Anyone have a working one to sell or plans for one?

Tom C.

Morning Tom, from our other thread, I am assuming and understood this to be a steam pump, it is not clear in this thread and many are assuming you are referring to a electric pump.

please confirm or deny